Windows XP soooo slow its unusable

The last few days my computer running XP is running so slow it's virtually unusable. Once it gets to the welcome screen, it takes at least an hour just to progress to the desktop, and then another long interval until the Windows start menu even comes up. If it gets that far, every attempt then to open or start a program or task is super slow as well.

I expect what brought this on is the Power company was out that day and installed a new wireless meter, and brought the power down in the process. However, I have the system plugged into a surge protector.

Anyone out there have any advice on what I could try aside from reinstalling Windows?

Thanks in advance.